Petty. Earnhardt. Johnson? A Debate Expands.

“Well, Earnhardt would have Petty in the wall,” said Humpy Wheeler, the race promoter and former president of Charlotte Motor Speedway, “and while they were discussing it, Jimmie would slip by both of them and win the race.”

Maybe. Maybe not. But it is an argument that fans are going to hear a lot more often in the next year if Johnson clinches the Sprint Cup championship as expected on Sunday in the season-ending Ford EcoBoost 400 at Homestead-Miami Speedway.

Johnson will not have to outrun anyone for the title. He needs merely to protect his comfortable 28-point margin over Matt Kenseth and 34-point advantage over Kevin Harvick. A 23rd-place finish or better in the 43-car field will lock it up no matter what happens. So barring a crash or engine failure, this championship is already decided.

Perhaps that was why there was little competitive banter among the three drivers still in contention during Thursday’s news conference at Homestead.

“Maybe because he’s ahead by 28 points,” Kenseth said.

Kenseth, the 2003 Cup champion, is the last to win a title under the old format in which drivers amassed points through an entire season. Since the 10-race playoff format was introduced in 2004, Johnson has won five times.

“The one thing that I don’t like is there’s one guy that thinks he has to win every single one of them,” Kenseth said, laughing, when asked about the playoff. “Doesn’t leave much for the rest of us.”

If Johnson clinches the title, it will be the sixth of his career and leave him one shy of Petty and Earnhardt, who are tied with seven titles apiece. For years, the argument over who was the greatest driver in Nascar history revolved around those two names. Now Johnson, along with his crew chief, Chad Knaus, is inserting himself into that debate with his performance.

But not with his words. Johnson will leave that to others. Twelve years into his career, he remains as consistently understated as he is accomplished.

“I’ve not been one to look at stats and pay attention to what’s been ahead of me and use that for motivation,” he said. “Of course, yes, I’d love to win this year. I’d love to win a seventh or an eighth. You go on and on. That’s what you would want to do.

“Is it realistic? I have no clue. Honestly, I haven’t spent a lot of time thinking about it.”

If Johnson will not say it, others have. Those include the longtime driver and broadcaster Kyle Petty, the son of Richard Petty. Kyle raced against his father, Earnhardt and Johnson when all three were in their prime.

“The King was a throwback to that rough-and-tumble Lee Petty, Buck Baker, seat-of-the-pants, do-it-all-yourself era,” Kyle Petty said of his father in a telephone interview. “Earnhardt was a guy who came along in that era but made that transition to being the driver and to being just the driver and understanding that part of it, and I think Jimmie has perfected the Earnhardt era and he is just a driving machine. That’s what he is.”

A machine?

“He’s like a computer feeding stuff back to Chad and making the adjustments,” Johnson’s team owner, Rick Hendrick, said Friday at Homestead. “He thinks about the race. Before we get to the racetrack, he’s planning on a strategy, the way he eats, the way he runs. You just don’t see that dedication that’s matched with talent that often.”

If Johnson clinches the title, he will have won at least one championship in three distinctly different racecars — the aerodynamically focused cars of 1992 to 2006, the boxy Car of Tomorrow that ran from 2007 to ’12 and this year’s redesigned Gen-6 model. It is yet another measure of the machinelike consistency of Johnson, Knaus and the No. 48 team.

Of course, it is not always easy for fans to love a machine or a computer, which might be part of the reason Johnson has not been embraced the same way Petty and Earnhardt were.

But that might be just a matter of time.

“We’re just in a period where he’s so dominant, a lot of people pull against him,” Kyle Petty said. “Give him another 10 or 12 years, he’ll be the darling of race fans, the media, everyone else.”

Who knows how many titles he will have won by then? Few people, if any, believe that Johnson, 38, is close to the end of his championship run and that he will finish with just six.

Ultimately, the argument about the best driver in Nascar history is very likely to be settled by Johnson.

“Yes, No. 6 is one step closer to seven,” Kyle Petty said. “But I think if you ask Jimmie, No. 6 is one step closer to eight. I don’t think he looks at seven. He’s not looking at a tie. He’s looking at moving to the top of the class.”